Virtual Colonoscopy - Topic Overview
How is it done?
Virtual colonoscopy is usually done in
the radiology department at a hospital or medical center. The test is most often done by a
doctor who specializes in performing and interpreting diagnostic imaging tests
(radiologist). The doctor may also have an
You will need to take off most of your clothes. You
will be given a gown to wear during the test.
First, you will be
asked to lie on your back on the table of the CT or MRI machine. A thin tube is inserted into the rectum through the anus. For CT, air or carbon dioxide gas will be pumped through the tube. (There may be some discomfort as the gas expands your colon.) For MRI, a contrast liquid will be given through the tube into the colon. This helps the doctor see all parts of your colon.
The table will slide into the CT or MRI machine so pictures of your colon can be taken. You may be asked to hold your breath when pictures are taken. This can help prevent blurry pictures. Then the procedure will be repeated while you lie face down.
The test usually takes about 10
How does a virtual colonoscopy differ from a regular colonoscopy?
Virtual colonoscopy has advantages and disadvantages
compared to a regular colonoscopy.
- Virtual colonoscopy is less invasive, safer,
and takes less time than a regular colonoscopy.
- A thin tube to
insert air into the colon is placed in the rectum rather than a long flexible
tube that is moved up your colon.
- No medicine to relax or sedate you is
needed, so you will be able to drive yourself home and resume normal
- Virtual colonoscopy can show the inside of a colon that is narrow due to inflammation or an abnormal growth.
- Virtual colonoscopy may not show polyps
smaller than 10 mm (0.4 in.).
- Virtual colonoscopy
is not covered by all health insurance plans. Check with your insurance plan
before having the test.
- If a polyp is found, regular colonoscopy will be needed
to confirm the diagnosis and remove the polyp so it can be looked at under a
- This is a newer test and isn't as widely available as regular colonoscopy.